Hitherto, there has been a problem in that it takes a cost and time to evaluate the quality of cement. For example, the compressive strength of mortar is measured by kneading cement, standard sand, and water in accordance with JIS R 5201 to mold a test piece and setting the test piece onto a compression tester at each time after curing for 1 day, curing for 3 days, curing for 7 days, and curing for 28 days. That is, it takes 28 days to determine a measurement result of the compressive strength of mortar, and hence a predicted value of the compressive strength of mortar cannot be obtained before shipping of cement.
In particular, in the recent cement manufacturing, the usage amount of industrial waste serving as a cement raw material or fuel for burning is increasing, and it is considered that there is an increase in the opportunity to change the quality of cement. Therefore, in order to prevent the abnormality of the quality of cement to be shipped, the importance of managing the quality of cement is increasing.
In order to solve the above-mentioned problem, Patent Literature 1 discloses a method of predicting the quality of cement involving analyzing a powder X-ray diffraction result of cement or clinker by a profile fitting method, and predicting a change in quality of cement (specifically, setting time period of cement and compressive strength of mortar) based on the crystal information of clinker mineral obtained from the analysis.
Further, Patent Literature 2 discloses a method of estimating the quality of cement involving applying information on the amounts of clinker constituent mineral and additives in cement, information on the crystal structure of the clinker constituent mineral, information on the amounts of minor components of clinker, and information on the fineness and 45 μm residue of cement, which are collected as quality management information in the operation of a cement manufacturing plant, to an estimation formula of the compressive strength of mortar determined based on multiple regression analysis among those information accumulated in the past and the actually measured data on the compressive strength of mortar, thereby estimating the compressive strength of mortar.
However, according to the methods of Patent Literatures 1 and 2, the qualities (for example, the fluidity of mortar, etc.) other than compressive strength and setting time period of mortar cannot be predicted. Further, the factors that influence the quality of cement are not limited to those disclosed in Patent Literatures 1 and 2, and various factors such as various conditions in a manufacturing process are considered to be involved in a complicated manner. Therefore, it has not been considered that the methods of Patent Literatures 1 and 2 have high accuracy.
On the other hand, a plurality of factors such as the flow rate of gas of a preheater are involved in some of the manufacturing conditions of cement in a complicated manner, as in the hydraulic modulus of a clinker raw material immediately before loading into a kiln, and hence it is difficult to predict some of the manufacturing conditions.
Then, there is a demand for a method capable of predicting the quality or manufacturing conditions of cement in a short time period and with high accuracy, taking various factors into consideration.